The effects of stage of growth and additives with or without cellulase on fermentation and invitro degradation characteristics of Leymus chinensis silage

摘要

This study evaluated the effects of different combinations of added lactic acid bacteria and cellulase applied at two growth stages on chemical composition and invitro rumen digestibility of Leymus chinensis silage. Fresh grass was harvested at early heading stage (S1) and late heading stage (S2), respectively, and ensiled with five additives: 200U cellulase (C)kg(-1) fresh matter (FM), 1x10(5) colony-forming units (cfu) Lactobacillus plantarum (LP)g(-1) FM, 1x10(5)cfu Lb.casei (LC)g(-1) FM, LP+C, LC+C and a control (CK). Four replicates of each treatment were weighed into 5-L plastic buckets, and the mini silos were stored at ambient temperature (similar to 30 degrees C) for 60d. Leymus chinensis harvested at S2 showed relatively higher neutral detergent fibre content, coliform bacteria count and lower crude protein content than S1. All additives decreased the pH and ammonia nitrogen (NH3-N) content of L.chinensis silage (P0001) except C. LP+C and LC+C decreased fibre content and increased water-soluble carbohydrate content (P0001). The silages were further anaerobically incubated invitro at 39 degrees C for 48h with buffered rumen fluids of lactating cows. Leymus chinensis harvested at S2 showed lower invitro dry-matter disappearance, NH3-N, total volatile fatty acid (VFA) content and higher average gas production rate (P005) than S1. In conclusion, Leymus chinensis should not be harvested too late. Compared with other treatments, a combination of Lb. casei (LC) with cellulase resulted in better fermented silage, but further testing is needed to confirm its efficacy.